1. Field of the Invention
The invention relates to a system and method for hardening rails. The rails can be profiled rails and can have different cross-sectional forms or shapes. The rails can also have a length of greater than about 50 meters. At least one part of the rail cross section is cooled over the entire rail length in a cooling medium. The system can utilize a cross displacement device arranged in an area of a roller table as well as an adjusting device and/or a manipulation gripper for moving the rail. At least one positioning device is also utilized. The system also includes at least one tank or trough which contains the cooling medium and a cooling bed.
2. Discussion of Background Information
Rails made of steel materials containing carbon, such as low-alloyed steels, are typically subjected to rolling and are then moved onto a cooling bed and allowed to cool. These rails throughout have a pearlitic structure and corresponding mechanical properties. In order to reduce wear on the rail, in particular, when the rail experiences with high axle loads as well as when the rail sill support high speed trains in narrow curves, it is known in the prior art to adjust the fine structure using a special thermal treatment such that at least the stressed rail head portion of the rail is provided with high hardness, high abrasion resistance, and can resist crack initiation, i.e., the rail in the track has improved wearing qualities.
A device for hardening rails which produces rails with fine structure can be achieve with cooling that utilizes a pass through a spray cooling device or which utilizes immersion in a cooling medium.
Although as a rule, continuous-pass spray cooling installations used for rail hardening are structured in a simple manner, they have the disadvantage of having large space requirements as well as requiring complex technology. Such systems also cannot efficiently rule out undesirable fluctuations in the quality of the rails in production. Furthermore, the precise coordination of cooling when rails have different cross-sectional profiles (switch rails, channel rails, bullheaded rails and the like), often cannot be carried out to the extent necessary using a continuous-pass spray device. Furthermore, a delay in the cooling of cross-sectional areas in the pass through can lead to uneven cooling medium impingements and thus to fluctuations in the hardness of the material over the length of the rail.
Spray tempering of the rail in order to leave it unmoved or to displace it alternately only slightly, preferably by the respective spray device spacing, has been proposed.
Furthermore, it is known to utilize one or more dipping baths for thermal tempering of rails and/or of parts of the cross section of rails.
In the area of sequential production of hardened rails with high rolling capacity, it has been proposed in AT 410 549 B to arrange at least two fluid cooling devices respectively parallel to an alignment means and to provide cross transport means with rolling stock support elements between the roller table rollers in order to carry out a movement of a rail from the roller table to manipulators of the cooling device. The rails are subsequently moved to the bearing area of a cooling bed. An increase of the throughput rate of rails through the tempering installation can be achieved in this manner. However, a running out from the roller frame, an alignment and a rotation of the rail on the roller table is not unrestrictedly possible with active alignment means.